Tire having floating reinforcement in the shoulder/sidewall

ABSTRACT

A radial ply tire ( 10 ) has a floating reinforcement ply on the inside shoulder/sidewall region of the tire. The reinforcement ply comprises ply rubber having a gauge sufficient to delocalize flexing in the tire shoulder/sidewall region, and in one embodiment may be reinforced with 0.50 to 6.0 phr fibers. Depending on the type of tire in which the reinforcement ply is used, the reinforcement has a total gauge of 0.005 inch to 0.175 inch (0.127 to 4.445 mm). When fiber is used in the illustrated embodiment, the fiber is oriented circumferentially in the tire.

BACKGROUND OF THE INVENTION

The present invention relates to radial pneumatic tires.

As materials improve, it has been the trend in the tire industry toreduce the gauges of tire components and the amount of material used tomake a tire. The reduction in the amount of material in a tire reducesits weight, its rolling resistance, and makes the tire run cooler. Ithas been found, however, that the gauge in all portions of a tire cannotbe reduced as much as the gauge in some portions of the tire and stillproduce a tire that has the durability and other properties of prior arttires with thicker gauges.

One of the ways in which the amount of material used in a tire can bereduced is to eliminate one or more of multiple components. For example,if a carcass ply can be made strong enough, two carcass plies can bereplaced with a single carcass ply. Monoply tires can be used inapplications where two carcass plies previously were needed.

It has been found that in radial pneumatic tires for highway driving,one area of weakness in a monoply tire is the shoulder area bridging thesidewall and crown of the tire.

It is known in the art to use a ribbon of ply rubber, about 0.020 inch(0.508 mm) gauge, in the shoulder/sidewall region of a high performancetire, and a similar ribbon having a higher gauge is used in light trucktires.

Until the present invention, no steel monoply carcass high performancetires ever passed durability tests. The inventors have discovered thatthe durability of a light weight tire is increased significantly by agum rubber ply having a specific gauge, or by a fiber loadedreinforcement ply, strategically placed in the construction of a tire.

SUMMARY OF THE INVENTION

The present invention is a tire that employs a floating reinforcementply bridging the intersection of a sidewall and crown area of thecarcass. The tire of the invention is a pneumatic tire comprising aradial ply carcass, a tread disposed radially outwardly of the crownregion of the carcass, and a belt assembly including at least one beltply interposed between the tread portion and the crown region incircumferential surrounding relation to the carcass. The floatingreinforcement ply is made from elastomeric material and in a preferredembodiment a fiber reinforced elastomeric material. Reinforcement fibersin a fiber reinforced ply are selected from the group consisting ofpolyamides, polyalkylenes, polyesters, cellulosics, inorganic fibers,aromatic polyamides and mixtures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a pneumatic tire made in accordancewith the present invention.

FIG. 2 shows one possible orientation of fibers in the reinforcement plyin a tire.

FIG. 2a shows a second possible orientation of fibers in the floatingreinforcement ply in the tire.

FIG. 3 illustrates one possible order of applying tire components to atire building drum.

FIG. 4 illustrates an alternative embodiment of a floating ply in a low(0.4) aspect ratio tire.

FIG. 5 illustrates a second alternative embodiment of a floating ply ina low (0.4) aspect ratio tire.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1, there is illustrated a radial carcasspneumatic tire 10 having a pair of substantially inextensible bead cores14 which are axially spaced apart with a radial carcass ply 12 extendingbetween the bead cores. The carcass ply is folded axially and radiallyoutwardly about each of the bead cores and is reinforced by cords whichare substantially parallel to each other and make an angle of about 65°to 90° with the equatorial plane (EP) of the tire. The cords of carcassply 12 are made of steel.

Tread 20 is disposed radially outward of the carcass ply in the crownarea of the tire and sidewalls 22 are disposed between the tread andbeads. Belt assembly 16 is interposed between the tread and the carcassply, the belt assembly having substantially the same width as the tread.In the illustrated embodiment, floating reinforcement ply 24 is disposedradially outward of carcass ply 12 in the shoulder area of the tirebridging sidewall area 26 and crown area 28 of carcass 12. Whenpneumatic tire 10 is a high performance tire, an overlay 18 is also usedin the construction.

In prior attempts to develop high performance mono carcass ply steelreinforced tires, the tires never passed durability tests because offailures in the shoulder area of the tire. It is theorized by theinventors herein that such prior failure occurred because theconsistency of green rubber during cure of a tire is reduceddramatically, i.e. the rubber acts in the same way as heated butterbefore it is cured, and the high modulus steel cords exhibit high stressin the shoulder area of the tire during expansion in the mold, whichstretches and makes thin the inner liner and ply in this area of thetire. The ply may be reduced from a gauge of 0.050 inch to 0.040 inch(1.27 to 1.016 mm) in the expanded tire, and the end count of thereinforcement cords may be reduced about 25%, e.g. from 22 e.p.i. to 15e.p.i. in the expanded tire. In a small percentage of tires, the plyreinforcement cords may cut through the liner in the mold. Also, in thecured tire, the thinner inner liner and ply permit the tire to flex in asmaller radius than would otherwise be possible, and the carcass cordsmay fatigue and possibly cut through the inner liner. By reinforcingthis area of the tire it was believed that the extra reinforcement inthe shoulder region would make the shoulder flex rounder, thus reducingfatigue, and would provide extra strength to reduce the possibility ofthe carcass cords cutting through the inner liner. In the latter regard,the addition of fibers to the reinforcement ply increases its greenstrength and helps prevent thinning of the liner and the ply in theshoulder region of the tire during curing in the mold, thus reducing thechances that the carcass cords will cut through the inner liner.

In the illustrated embodiment, the belt assembly includes two plies,each of which comprises cords of high modulus material extendingparallel to one another in each belt ply and making opposed angles withrespect to the equatorial plane of the tire.

Those skilled in the art will recognize that tires of the invention maycomprise one to four belt plies.

As used herein, similar numbers may be used to identify similar portionsof the invention in different drawings, but may be subscripted withletters to identify modifications.

“Radial” and “radially” refer to directions that are radially toward oraway from the axis of rotation of the tire, and the term “floating”indicates no wraparound attachment to other components of the tire.

Floating reinforcement ply 24 has a total gauge of 0.005 to 0.175 inch(0.127 to 4.445 mm), preferably 0.010 to 0.150 inch (0.254 to 3.81 mm).In a preferred embodiment, the floating reinforcement ply is loaded withfiber reinforcement. The reinforcement fibers may comprise polyamides,polyalkylenes, polyesters, cellulosics, inorganic fiber, aromaticpolyamides and mixtures thereof. Specifically the fibers may be selectedfrom the group consisting of nylon, polyethylene terephthalate,polyethylene napthalate, aramid, glass, metal, rayon, polyethylene,polypropylene, cotton, or mixtures thereof.

Referring to FIGS. 2 and 2a, floating reinforcement ply 24 may bereinforced with 0.5 to 6 phr (parts by weight per hundred parts byweight rubber) fibers, preferably 1.5 to 4 phr fibers. In a highperformance tire it is preferred that 1 to 2 phr fibers are used, and inthe illustrated embodiment, 1.5 phr aramid pulp fibers are used. Becausecalendering causes the fibers to orient with the linear length directionof the ply, the fibers are oriented in the tire in the circumferentialdirection in the illustrated embodiment, see e.g. FIG. 2a. Those skilledin the art will recognize that other orientations of the fiber in theply will work, e.g. radial orientation or axial orientation, and it isbelieved theoretically that random orientation will work best, see FIG.2.

The aramid used in the illustrated embodiment was obtained from DuPontde Nemours Inc. in a master batch identified as Merge 6F722.

The floating reinforcement ply is 10 mm to 200 mm wide and may beapplied to the building drum as one of the early components in the tireconstruction. With reference to FIG. 3, in the illustrated embodiment,two inner liners are applied to the building drum in the first step ofthe tire construction, followed by toe guards 42, floating reinforcementplies 24, carcass ply 12, and wedges 44. The beads 14 are then set intoposition followed by the addition of apex 46. The tire components areexpanded and the edges of the carcass plies are turned up over thebeads, followed by the addition of further tire components such as anoptional chafer 48, and then sidewalls 22, belts 16, optional overlay 18and tread 20.

Those skilled in this art will recognize that tire components can beadded in a different order and different components can be used,depending on the kind of tire being built, for example some tires aremade with one turn of inner liner. Those skilled in the art will alsorecognize that different placement of the floating reinforcement ply inthe tire construction can be used, e.g., radially outward of the carcassplies, it being understood that such floating reinforcement plies willalways be located in the shoulder of the tire bridging thesidewall/crown region of the tire.

With reference now to FIG. 4, in one embodiment, floating reinforcementply, 24 a may be shaped like a crescent, i.e. tapered at both edges.

In an alternative embodiment, with reference to FIG. 5, the floating plymay comprise a number of layered, offset plies. The offset plies havegenerally the same effect as the crescent shape ply and are used toobtain the total gauge needed since some single plies having the totalthickness needed would trap air at the ply edges and might localizeshoulder flex points.

Other ply arrangements, for example layered plies where each successivelayer is narrower than the last may be used. Other arrangements will beapparent to those skilled in the art.

It has been found that in a steel reinforced monoply tire, the gauge offloating reinforcement in the shoulder area of the uncured tire, ingeneral, must be about twice the gauge required in such ribbonreinforcement in polyester reinforced monoply tires. Also, it has beendiscovered that steel reinforced monoply tires having different aspectratios require different amounts of sidewall/crown area reinforcement.Accordingly, in a high performance steel monoply tire having an aspectratio of 0.5 or less, the minimum gauge of gum rubber floatingreinforcement is about 0.075 inch (1.905 mm), and reinforcement having agauge 0.075 to 0.175 inch (1.905 to 4.445 mm) may be used. Those skilledin the art will recognize that if the gauge of the floatingreinforcement is too thick, or the reinforcement is made too stiff, thereinforcement will hinder the flexing of the tire and may ultimatelyreduce the durability of the tire.

Similarly, in high performance monoply steel tires having an aspectratio of 0.5 to 0.8, it has been found that the minimum gauge offloating reinforcement is about 0.020 inch (0.508 mm), and reinforcementhaving a gauge of 0.020 to 0.085 inch (0.508 to 2.159 mm) may be used.Those skilled in the art will recognize that as the aspect ratio of thetire increases, the amount of reinforcement needed in the shoulder ofthe tire decreases, and the lower gauge reinforcement will be used inthe higher aspect ratio tires.

Referring again to FIGS. 2 and 2a, when fiber reinforcement is used,floating reinforcement ply 24 comprises fiber 32 encased in a ply rubber34. In either case, in the illustrated embodiment, ply rubber 34 is thesame rubber used in the carcass ply and has a 100% modulus of 5 to 6N/mm², a tensile strength of 15 to 25 N/mm², preferably 18 to 25 N/mm²,and an elongation at break of 300 to 450%, preferably 325 to 400%, and atack of 0 to 5, preferably 2 to 5, and more preferably 3½ to 4.

In the illustrated embodiment, when the ply rubber was loaded with 1.5phr aramid fiber, the ply demonstrated a 100% modulus of 7 to 8 N/mm², atensile strength of 16 to 19 N/mm², and an elongation at break of 340 to350%. The addition of the fiber also increases the tear strength of therubber by 30% or more.

In illustrated embodiments of the invention, it has been found that whena floating reinforcement ply in a high performance tire is reinforcedwith 1 to 2 phr aramid fibers, satisfactory results are obtained whenthe gauge of floating reinforcement ply 24 in a tire having an aspectratio of 0.5 to 0.8 is 0.020 to 0.060 inch (0.508 to 1.524 mm), andsatisfactory results are obtained when the gauge of the floatingreinforcement ply in a high performance tire having an aspect ratio lessthan 0.50 is 0.040 to 0.100 inch (1.016 to 2.54 mm).

The invention is further illustrated with reference to the followingexample.

EXAMPLE 1

In the early development of tires of the invention carcass constructionsof tires size P275/40ZR17 using 0.18 mm wire at 18 epi and a 0.040″(1.016 mm) gauge floating reinforcement were tried. The data in Table 1below shows that the tires failed the low inflation endurance test anddid not meet minimum standards in the fatigue capacity test (130% forthe maximum fatigue capacity and 100% for the low maximum fatiguecapacity are needed to pass the test).

TABLE 1 Development Tires Const. 83B 83C Wire 1 + 5 × .18 @ 18 1 + 5 ×.18 @ 18 Floating Reinforcement 1-.040″ gum 1-.040″ gum Total Ribbon GA.040″ .040″ Bead Strap Strap Plunger Residual No No Burst Residual No NoLow INF Endurance 2355 SWF 2925 2920 SWF SWF 3410 OK Fatigue Capacity115/80 111/0 SPL TRD ATE 30,513 28,635 (45,000 SF) SWF SWF 35,000 31,23029,609 SWF 35,000 35,000 34,669 SWF indicates sidewall failure.

EXAMPLE 2

Tires size P195/75R14 were constructed substantially as illustrated inFIGS. 3 and 3a using a floating reinforcement ply which was reinforcedwith 1.5 phr aramid pulp fiber oriented in the circumferential directionof the tire. The floating reinforcement strip had a gauge of 0.040 inch(1.016 mm) and was 63.5 mm wide.

Tires were constructed using various combinations of carcassreinforcement, beads and floating reinforcement plies. For example, thetire showing the best properties was made using 1+5×0.16 mm steel cordreinforcement at 24 ends per inch as carcass ply (monoply) reinforcementand a Hex 3-4-3-2 bead made with 0.050 inch (1.27 mm) diameter wire. Acomparison tire was made using 1+5×0.18 mm steel cords at 18 ends perinch as monoply reinforcement and a 4×5 strap bead made with 0.038 inch(0.965 mm) diameter wire, and a 0.040 inch (1.016 mm) gauge ply rubberribbon made without reinforcement was added to the tire in place of afloating reinforcement ply. Other constructions are illustrated below.

The constructions were subjected to the fatigue capacity test (fat captest) where in one portion of the test two tires are tested at ratedloads for 100 miles (160.93 km), and 100 pounds (45.36 kg) are added tothe load at 100 mile (160.93 km) intervals until the tires fail, usuallybetween 2000 and 3000 miles (3,218.68 to 4,828.03 km). In a secondportion of the test, 100 pounds (45.36 kg) is added to the load ofanother set of tires every 800 miles (1,287.48 km) until the tires fail.

The data on the average loads achieved in the two portions of the testare graphed, and the slope of the line between the two average loads isused to obtain a fatigue capacity rating which is used to predict theloaded durability of the tire. To pass the test, the tire must achieve amaximum load capacity of 130% of the rated load and a low fatiguecapacity of 100% of the rated load.

The tires were inflated to 35 psi (2.46 kg/cm²)and were given an initialload of 1400 pounds (635.04 kg). The test was run at 50 mph (80.47km/hr).

The inventors have observed that the tires with the highest percentageof maximum load are the tires which otherwise have the best overalldurability.

The differences in the constructions tested are summarized in Table 2,the specifics of the fatigue capacity test are set forth in Table 3, andthe fatigue capacity results are summarized in Table 4.

TABLE 2 Const. on Tire Ply Ribbon Bead Belts J 1 + 5 × .16 @ 24 epi.020″ 4 × 5 Strap Type I .038″ Wire K 1 + 5 × .18 @ 18 epi .020″ 4 × 5Strap Type I .038″ Wire P 1 + 5 × .16 @ 24 epi .020″ Hex 3-4-3 Type I.050″ Wire Q 1 + 5 × .16 @ 24 epi .040″ HEX 3-4-3 Type I 1.5 .050″ WireFlex Pulp H 1 + 5 × .18 @ 18 epi .040″ 4 × 5 Strap Type II .038 Wire E1 + 5 × .18 @ 18 epi .040″ 4 × 5 Strap Type II .038 Wire B 1 + 5 × .18 @14 epi .040″ 4 × 5 Strap Type I .038″ Wire C 1 + 5 × .18 @ 14 epi .040″4 × 5 Strap Type I .038″ Wire G 1 × .18 @ 80 epi .020″ 4 × 5 Strap TypeI .038″ Wire F 1 + 5 × .18 @ 18 epi .020″ 4 × 5 Strap Type I .038″ Wire

Type I belts are made with 2+2×0.25 mm steel cord @20 epi and Type IIbelts are made with 2×0.30 mm steel cords @24 epi.

TABLE 3 Loading Failure Removal Const. Dash lbs/mi Mileage Load Mode J 5100/100 2773 4100 Sidewall Failure 6 100/100 2773 4100 Sidewall Failure8 100/800 12200 2900 Sidewall Failure 7 100/800 11462 2800 SidewallFailure K 2 100/100 2200 3500 Bead Failure 3 100/100 2200 3500 BeadFailure 5 100/800 11200 2700 Bead Failure 4 100/800 11200 2700 SidewallFailure P 1 100/100 2626 4000 Sidewall Failure 4 100/100 2417 3800Sidewall Failure 6 100/800 10499 3700 Sidewall Failure 7 100/800 108692700 Sidewall Failure Q 4 100/100 2200 3500 Bead Failure 5 200/100 22003500 Bead Failure 6 100/800 12649 2900 Sidewall Failure 7 100/800 134063000 Bead Failure E 3 100/100 2700 4000 Chunking in Tread Area 4 100/1002700 4000 Crown Failure 16 100/800 11600 2800 Sidewall Failure 25100/800 12075 2900 Chunking in Tread Area F 2 100/100 2300 3600 CrownFailure 1 100/100 2300 3600 Chunking in Tread Area 4 100/800 10400 2600Crown Failure 5 100/800 10725 2700 Crown Failure G 3 100/100 2800 4100Chunking in Tread Area 4 100/100 2800 4100 Crown Failure 8 100/800 131003000 Chunking in Tread Area 12 100/800 13400 3000 Crown Failure H 1100/100 2800 4100 Sidewall Failure 5 100/100 2650 4000 Crown Failure 6100/800 13025 3000 Sidewall Failure B 9 100/100 2200 3500 Crown Failure8 100/100 2250 3600 Crown Failure 11 100/800 9150 2500 Crown Failure 10100/800 9125 2500 Crown Failure C 28 100/100 2200 3500 Crown Failure 29100/100 2400 3700 Crown Failure 30 100/800 10125 2600 Bead Failure 31100/800 10600 2700 Chunking in Tread Area

TABLE 4 Fat Cap Fat 90% Line % Max Low Fat Cap Const. Cap Limits SlopeLoad % Max Load E 2221 +−179 1779 159 146 F 2130 +−179 1470 152 139 G2398 +−0 1703 171 171 H 2348 +−253 1703 168 150 B 1926 +−179 1624 138125 C 2130 +−400 1470 152 124 J 2166 +−179 1934 155 142 K 2262 +−0 1238162 162 P 2044 +−358 1856 146 120 Q 2649 +−179 851 189 176

EXAMPLE 3

Size P275/40ZR17 tires were made with steel reinforced mono carcassplies. As in the higher aspect ratio tires of example 2, different wirereinforement and different bead wires were used in differentconstructions. Wire designated “A” in the constructions refers to1+5×0.16 mm wire @28 epi in a carcass having a 0.052″ (1.3208 mm)treatment gauge. “B” wires in the constructions refers to 1+5×0.18 mmwire @22 epi in the carcass with 0.055 inch (1.397 mm) treatment gauge.The constructions and the results of low inflation endurance tests areprovided in Table 5 and the results are summarized in Table 6.

In Table 5, the floating reinforcement ply is defined by the number ofplies used and the gauge of each ply. For example “2-0.040” means two0.040″ (1.016 mm) gauge offset plies were used. “EMT-INS” means acrescent shaped insert was used in the shoulder region, i.e. the plieswere tapered on both edges. The same ply rubber was used for all thefloating plies, including the fabric ply (ply) and the fiber loaded ply(Pulp).

TABLE 5 P275/40ZR17 EF1 Steel Ply Const. 41A 41B 41C 41D 41E 41F 41G 41HH1J 41L 41K Wire A A A A A A B B A A B Floating 2.040″ 2-80D EMT EMT 2-1-.040″ 2-.040″ 1-.040″ 1-.040″ 2- 2-.040″ Reinforcement Pulp Ply INSINS .040″ .040″ Total Ribbon GA 0.08″ .084″ .080″ .080″ .080″ 0.040″.080″ .040″ .040″ .080″ .080″ Bead HEX HEX HEX PYRMD HEX HEX HEX HEX HEXHex HEX Plunger Residual 4216 NO 5080 5455 5285 5181 4960 NO 5069 42164824 Burst Residual 476 NO 490 481 330 NO 335 CRN NO NO 376 345 CRN CRNCRN CRN CRN CRN Low INF 3410 3085 3410 3410 3410 1165 3410 3056 31303410 3410 OK Endurance OK SWF OK OK OK SWF OK SWF SWF OK 3410 OK 34103146 3410 3410 3410 3410 OK 3410 OK 3410 3410 OK 3410 OK SWF OK OK OKSWF OK Fatigue Capacity 163/ 179/ 135 114 SPL TRD ATE 15K 45K Run(45,000 SF) Run

In the low inflation endurance test, tires are inflated to 15 psi (1.05kg/cm²) and run at 55 mph (88 km/h) for 3410 miles (5,487.86 km). In thetest the tire is run for 4 hours at 88% of rated load, 6 hours at ratedload, 21 hours at 108% of rated load and 31 hours at 115% of rated load.At the end of the test the tire passes if it survives.

The plunger test is a DOT test requirement on a new tire. The bursttest, where water is pumped into the tire under pressure until the tirebreaks, is a Goodyear test used to evaluate the residual strength of atire after passing the low inflation endurance test.

In the Accelerated Treadwear and Endurance test (ATE), tires are mountedon a vehicle and the front tires are inflated to 26 psi (1.83 kg/cm²)and loaded to 100% rated load, and the rear tires are inflated to 35 psi(2.46 kg/cm²) and loaded to 110% rated load. The tires are run on Texashighways that are laid out to comprise 3% gravel (golf ball size butsharp), 37% secondary roads, and 60% interstate highways at 65 mph (104km/hr). To pass the test, the average survival of the tires must be atleast 30,000 miles (48,280.32 km). Goodyear's internal criteria is thatthey must average 45,000 miles (72,420.48 km).

In the tables, the data shows that both B constructions and both Hconstructions failed, which suggests that the construction is inherentlyflawed. The ‘B’ construction used a fabric ply floating reinforcementwhich suggests that if the floating reinforcement ply is too stiff, itcontributes to the destruction of the tire. The ‘H’ construction used0.040 inch (1.016 mm) gauge gum rubber as the floating reinforcementply, which suggests that 0.040 inch (1.016 mm) gum rubber with B wirereinforcement does not provide enough reinforcement.

The ‘F’ and ‘J’ constructions are made with ‘A’ wire reinforcement and a0.040 inch (1.016 mm) gum floating reinforcement ply, and since some ofthe tires survived, this suggests that 0.040 inch (1.016 mm) gumfloating reinforcement may be sufficient reinforcement in some lowaspect ratio tire constructions. The successful tire constructions allused at least 0.080 inch (2.032 mm) gum rubber, or 0.080 pulp reinforcedrubber. In view of the fact that some tires survived with 0.040 inch(1.016 mm) gum reinforcement, it is believed that 0.040 pulp reinforcedfloating reinforcement plies will provide sufficient reinforcement inthe shoulder region on these tires.

Table 6 summarizes the results for the constructions tested.

TABLE 6 # Build # Pass Percentage 2 Pulp .080 1 1 100% 41A 2 FAB .088 10 Zero 41B Terrible 2 GUM .080 3 3 100% 41E, G, K 1 EMT .080 2 2 100%41C, D 1 GUM .040 3 0 Zero 41F, H, J (close)

The embodiments of the invention described above should be considered asillustrative and not as limiting the scope of the invention as definedin the following claims.

What is claimed is:
 1. A high performance pneumatic tire (10) comprisinga pair of substantially parallel annular beads (14), a single radial plycarcass (12) wrapped around said beads (14), a tread (20) disposedradially outwardly of the crown region (28) of the carcass (12),sidewalls (22) disposed between said tread (20) and said beads (14), abelt assembly (16) including at least one belt ply interposed betweenthe tread portion and the crown region (28) in circumferentialsurrounding relation to the carcass (12), the at least one belt plycomprising reinforcement cords extending parallel to one another, andsaid carcass ply (12) is made with steel reinforcement cords and afloating reinforcement ply (24) bridges a crown portion (28) and asidewall portion (26) of the carcass (12) radially inward of saidcarcass ply (12), wherein said floating reinforcement ply (24) isselected from the group consisting of (a) gum rubber having a 100%modulus of 5-6 N/mm² and a gauge of 0.075 to 0.175 inch (1.905 to 4.445mm) when said tire has an aspect ratio of less than 0.5, and (a1) agauge of 0.02 to 0.085 inch (0.508 to 2.159 mm) when said tire has anaspect ratio of 0.5 to 0.8, and (b) short fiber reinforced gum rubber,wherein the short fiber reinforcement comprises 1-2 parts fiber perhundred parts rubber having a 100% modulus of 7-8 N/mm² and a gauge of0.02 to 0.06 inch (0.508 to 1.524 mm) when the aspect ratio of the tireis 0.5 to 0.8, and (b1) a gauge of 0.04 to 0.10 inch (1.01 to 2.54 mm)when the aspect of the tire is less than 0.5, and wherein gum rubber insaid floating reinforcement ply (24) contains natural rubber and has atensile strength of 15 to 25 N/mm² and an elongation at break of 300 to450%.
 2. The pneumatic tire of claim 1 wherein the reinforcing fibersare selected from the group consisting of polyamides, polyalkylenes,polyesters, cellulosics, inorganic fibers, aromatic polyamides andmixtures thereof.
 3. The pneumatic tire of claim 2 wherein reinforcingfibers in said reinforcement are selected from the group consisting ofnylon, polyethylene terephthalate, polyethylene napthalate, aramid,glass, metal, rayon, polyethylene, polypropylene, cotton and mixturesthereof.
 4. A high performance pneumatic tire comprising a single radialply carcass (12), a tread (20) disposed radially outwardly of a crownregion (28) of the carcass (12), a belt assembly (16) having an overallwidth substantially equal to that of the tread (20) interposed betweenthe tread portion (12) and the crown region (28) in circumferentialsurrounding relation to the carcass (12), whereby the belt assembly (16)includes a first radially innermost belt ply and a second radiallyoutermost belt ply, each belt ply having reinforcement cords extendingparallel to one another and reinforcement cords in each belt ply havingopposite cord angle orientation compared to the other, and wherein saidangle is 15° to 35° with respect to the equatorial plane of the tire(10), said tire having an aspect ratio of 0.8 or less, wherein carcassreinforcement cords are made of steel and a floating reinforcement ply(24) comprising fiber reinforced elastomeric material is locatedradially inward of the carcass ply (12) and bridging a crown (28) and asidewall portion (26) of the carcass (12) and said floating reinforcingply (24) is loaded with 1.5 phr aramid fibers and said floatingreinforcing ply has a 100% modulus of 7 to 8 N/mm², a tensile strengthof 16 to 19 N/mm², and an elongation at break of 340 to 350%, saidfloating reinforcement ply having a gauge of 0.02 to 0.06 inch (0.508 to1.524 mm) when the aspect ratio of the tire is 0.5 to 0.8, and a gaugeof 0.04 to 0.10 inch (1.01 to 2.54 mm) when the aspect ratio of the tireis less than 0.5.
 5. The tire of claim 4 wherein said carcass ply (12)is reinforced with 1+5×0.16 mm @11 epc (@28 epi) steel cords.
 6. Thetire of claim 4 wherein said carcass ply (12) is reinforced with1+5×0.18 mm @8.7 epc (@22 epi) steel cords.